The objective of this research is to understand glucocorticoid-receptor interactions and their job in mediating glucocorticoid action. The cell model is the glucocorticoid-responsive AtT-20 cell line. We have demonstrated that these cells contain both soluble and membrane binding sites. Our present goals are to: 1. complete characterization of the membrane receptor and determine the affinity, specificity and size of the solubilized receptor. 2. Determine if glucocorticoids vary in their ability to cause nuclear activation (as measured by DNA cellulose binding) and if that variation can be related to their ability to promote nuclear translocation in intact cells. 3. Compare the ability of various glucocorticoids to promote nuclear translocation with their ability to inhibit ACTH mRNA biosynthesis.